Juniper T640 Hardware Guide

between 40°F (4° C) to 90°F (32° C). Note that if the material flakes, or becomes brittle
when rubbed or deformed, it is no longer usable.
CAUTION: Always keep both air filters in place while the router is operating.
Because the fans are very powerful, they could pull small bits of wire or other
materials into the router through the unfiltered air intake. This could damage
the router components.
Related
Documentation
T640 Cooling System Description on page 31•
• T640 Clearance Requirements for Airflow and Hardware Maintenance on page 122
• Replacing a T640 Air Filter on page 281
Maintaining the T640 Fan Trays
Purpose For optimum cooling, verify the condition of the fans.
Action On a regular basis:
• Monitor the status of the fans. The fan trays each contain multiple fans that work in
unison to cool the router components. If one fan fails, the host subsystem adjusts the
speed of the remaining fans to maintain proper cooling. A red alarm is triggered when
a fan fails, and a yellow alarm is triggered when a fan tray is removed.
• To display the status of the fans, issue the show chassis environment command or
show chassis fan command.
During normal operation, the fans in each fan tray function at less than full speed.
For the standard front fan trays and standard rear fan tray with eight fans, the output
for the show chassis environment command is similar to the following:
user@host> show chassis environment
Class Item Status Measurement
...
Fans Top Left Front fan OK Spinning at normal speed
Top Left Middle fan OK Spinning at normal speed
Top Left Rear fan OK Spinning at normal speed
Top Right Front fan OK Spinning at normal speed
Top Right Middle fan OK Spinning at normal speed
Top Right Rear fan OK Spinning at normal speed
Bottom Left Front fan OK Spinning at normal speed
Bottom Left Middle fan OK Spinning at normal speed
Bottom Left Rear fan OK Spinning at normal speed
Bottom Right Front fan OK Spinning at normal speed
Bottom Right Middle fan OK Spinning at normal speed
Bottom Right Rear fan OK Spinning at normal speed
Rear Tray Top fan OK Spinning at normal speed
Rear Tray Second fan OK Spinning at normal speed
Rear Tray Third fan OK Spinning at normal speed
445Copyright © 2017, Juniper Networks, Inc.
Chapter 32: Maintaining Components

Juniper T640 Specifications

General

Brand	Juniper
Model	T640
Category	Network Router
Language	English